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| 1 | The roles of heterogeneous chemical processes in the formation of an air pollution complex and gray haze显示文摘Urban and regional air pollutions are characterized by high concentrations of secondary pollutants such as photo-oxidants (mainly ozone) and fine particulate matter,which are formed through chemical reactions of the primary pollutants emitted from various sources.The accumulation of these pollutants under stagnant meteorological conditions results in the formation of gray haze,reducing visibility and causing major impacts on human health and climate.In an air pollution complex,the coexistence of high concentrations of primary and secondary gaseous and particulate pollutants provides a large amount of reactants for heterogeneous reactions on the surface of fine particles;these reactions change the oxidizing capacity of the atmosphere,as well as chemical compositions along with the physicochemical and optical properties of particulate matter,thereby accelerating formation of the air pollution complex and gray haze.Using in situ technologies,such as diffuse reflectance infrared Fourier-transform spectroscopy and single-particle Raman spectroscopy,we systematically investigated the reaction kinetics and mechanisms of gaseous pollutants (i.e.,NO2,SO2,O3,and formaldehyde) on the surfaces of the major components of atmospheric particles such as CaCO3,kaolinite,montmorillonite,NaCl,sea salt,Al2O3,and TiO2.We found that the main reaction products were sulfate,nitrate,or formate,which can change the hygroscopicity and light extinction parameters of those particles significantly.By analyzing the reaction kinetics of these heterogeneous reactions,we identified synergetic mechanisms of the three ternary reaction systems,i.e.,NO2-particlesH2O,SO2-particles-O3,and organics/SO2-particles–UV illumination.These synergetic mechanisms can provide experimental and theoretical bases for understanding the feedback mechanisms and nonlinear processes in the formation of an air pollution complex and gray haze. | ZHU Tong,SHANG Jing & ZHAO DeFeng State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and Engineering,Peking University,Beijing 100871,China | 2011 | Science China Chemistry2011，54，1： | 24 |
| 2 | Heterogeneous reactions on the surface of fine particles in the atmosphere显示文摘Fine particles play an important role in the atmosphere. Research on heterogeneous reactions on the surface of fine particles is one of the frontier areas of atmospheric science. In this paper, physical and chemical characteristics of fine particles in the atmosphere and the interactions between trace gases and fine particles are described, methods used in heterogeneous reactions research are discussed in detail, progress in the study of heterogeneous reactions on the surface of fine particles in the atmosphere is summarized, existing important questions are pointed out and future research directions are suggested. | DING Jie & ZHU Tong State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences, Peking University, Beijing 100871, China Correspondence should be addressed to Zhu Tong (e-mail:tzhu@ pku.edu.cn) | 2003 | Chinese Science Bulletin2003，48，21： | 24 |
| 3 | Parameter determination to calculate water environmental capacity in Zhangweinan Canal Sub-basin in China显示文摘Zhangweinan canal sub-basin (ZWN) has the most serious water resource shortage and water pollution problems in north of China.To calculate the water environmental capacity in ZWN,determination methods for design flow rates and degradation coefficients were discussed in this study.Results showed that 90% and 50% hydrological guarantee flow rates were suitable to be the design flow rates for rainy and dry seasons,respectively.Degradation coefficients of COD Mn and NH 3 -N were 0.25 day -1 and 0.15 day -1 for branch streams and 0.5 day -1 and 0.25 day -1 for mainstreams,respectively in ZWN.With one-dimensional water quality simulation model,water environmental capacities were calculated to be 82,139 tons/yr for COD Mn and 2394 tons/yr for NH 3 -N in ZWN. | Yingxia Li ,Ruzhi Qiu,Zhifeng Yang,Chunhui Li,Jingshan Yu State Key Laboratory of Water Environment Simulation,School of Environment,Beijing Normal University,Beijing,100875,China. | 2010 | Journal of Environmental Sciences2010，22，6： | 23 |
| 4 | Island partition of the distribution system with distributed generation显示文摘In this paper, a novel optimum island partition model based on Tree Knapsack Problem (TKP) is presented for the distribution system integrated with distributed generation (DG), and a Depth-first Dynamic Programming Algorithm (DPA) is used to solve this model. With the considerations of the load priority, controlled/uncontrolled loads, and the constraints of power balance, voltage and equipment capacity, the model can meet the practical engineering requirements very well. The island partition problem of the distribution system integrated with multiple DGs is first decomposed into multiple TKPs, each of which is solved by DPA respectively. Then, the initial optimum island partition scheme is gained through an island combination procedure, and the final island partition scheme is obtained after feasibility checking and adjustment. Since the algorithm proposed owns the advantages of strong theoretical foundation and low computational complexity, it can find the approximate optimal solution within a limited time. The results of examples demonstrate the validity of the new model and algorithm. | WANG XuDong & LIN JiKeng* Key laboratory of Power System Simulation and Control of Ministry of Education, Tianjin University, Tianjin 300072, China | 2010 | Science China(Technological Sciences)2010，53，11： | 21 |
| 5 | Simulation of influence of multi-defects on long-term working performance of high arch dam显示文摘As an integrated structure,an arch dam is assumed to bear loads in its design consideration.However,multi-defects,such as cracks and the opening of transverse joints,are unavoidable during construction and operation.Multi-defects will reduce the structural integrity and stiffness of the dam and affect its working performance and degree of safety.In the current paper,a numerical model of defects and a simulation method of a high arch dam are introduced.The Chencun arch dam is analyzed as a case study.An entire course simulation analysis of the Chencun arch dam from construction to operation is carried out,through which the opening of the transverse and longitudinal joints,formation of cracks,and their influence on deformation and stress of the dam are studied.According to the results of the analysis,appropriate measures should be adopted to prevent the development of cracks,and observation should be strengthened for a more timely discovery of risks. | ZHANG GuoXin ,LIU Yi,ZHENG CuiYing & FENG Fan State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin,Beijing 100038,China China Institute of Water Resources and Hydropower Research,Beijing 100038,China | 2011 | Science China(Technological Sciences)2011，54，S1： | 17 |
| 6 | Degradation of 4-chlorophenol in aqueous solution by γ-radiation and ozone oxidation显示文摘The degradation of 4-chlorophenol (4-CP) by using gamma rays generated by a 60Co source in the presence of O3 was investigated. The radiolysis of 4-CP and the kinetics of 4-CP min-eralization were analyzed based on the determination of total organic carbon (TOC). The influence of initial 4-CP concentration and the free radicals scavengers (such as NaHCO3 and t-butanol) on the 4-CP degradation was also studied. The results showed that when the radiation rate was 336 Gy·min?1, 4-chlorophenol at concentration of 10 mg·L?1 could be completely degraded at the radiation dose of 2 kGy. The degradation of 4-chlorophenol could be described by a first-order reaction model, the rate constant of 4-CP degradation by combined ozonation and radiation was 0.1016 min?1, which was 2.4 times higher than the sum of radiation (0.0294 min?1) and ozonation (0.0137 min?1). It re-vealed that the combination of radiation and ozonation resulted in synergistic effect, which can re-markably increase the degradation efficiency of 4-CP. | HU Jun1, WANG Jianlong1,2 & CHEN Rong1 1. Laboratory of Environmental Technology, Institute of Nuclear Energy Technology, Tsinghua University, Beijing 100084, China 2. State Key Joint Laboratory of Environmental Simulation and Pollution Control, Tsinghua University, Beijing 100084, China Correspondence should be addressed to Wang Jianlong | 2006 | Science China Chemistry2006，49，2： | 16 |
| 7 | Economical cascadic multigrid method (ECMG)显示文摘In this paper, an economical cascadic multigrid method is proposed. Compared with the usual cascadic multigrid method developed by Bornemann and Deuflhard, the new one requires less iterations on each level, especially on the coarser grids. Many operations can be saved in the new cascadic multigrid algorithms. The main ingredient is the control of the iteration numbers on the each level to preserve the accuracy without over iterations. The theoretical justification is based on the observations that the error reduction rate of an iteration scheme in terms of the smoothing property is no longer accurate while the iteration number is big enough. A new formulae of the error reduction rate is employed in our new algorithm. Numerical experiments are reported to support our theory. | Zhong-ci SHI~1 Xue-jun XU~(1+) Yun-qing HUANG~2 ~1 LSEC,Institute of Computational Mathematics,Academy of Mathematics and Systems Science,Chinese Academy of Sciences,Beijing 100080,China ~2 Hunan Key Laboratory for Computation and Simulation in Science and Engineering,Institute for Computational and Applied Mathematics,Xiangtan University,Xiangtan 411105,China | 2007 | Science China Mathematics2007，50，12： | 14 |
| 8 | APPLICATION OF SWAT MODEL IN THE UPSTREAM WATERSHED OF THE LUOHE RIVER显示文摘In the Huanghe (Yellow) River basin,soil erosion is a serious problem,while runoff and sediment yield simulation has not been extensively studied on the basis of GIS (Geographic Information System) and distributed hydrological model. GIS-based SWAT (Soil and Water Assessment Tool) model was used to simulate runoff and sediment in the Huanghe River basin. The objective of this paper is to examine the applicability of SWAT model in a large river basin with high sediment runoff modulus,which could reach 770t/(km2·a). A two-stage 'Brute Force' optimization procedure was used to calibrate the parameters with the observed monthly flow and sediment data from 1992 to 1997,and with input parameters set during the calibration process without any change the model was validated with 1998-1999’s observed data. Coefficient of examination (R2) and Nash-Suttcliffe simulation efficiency (Ens) were used to evaluate model prediction. The evaluation coefficients for simulated flow and sediment,and observed flow and sediment were all above 0.7,which shows that SWAT model could be a useful tool for water resources and soil conservation planning in the Huanghe River basin. | ZHANG Xue-song, HAO Fang-hua, CHENG Hong-guang, LI Dao-feng (State Key Laboratory of Water Environment Simulation,Institute of Environmental Sciences, Beijing Normal University,Beijing 100875,P. R. China) | 2003 | Chinese Geographical Science2003，13，4： | 14 |
| 9 | Simulation of freezing and melting of soil on the northeast Tibetan Plateau显示文摘Using observational data spanning the period from February to December 2009 and recorded at the Suli station in Qinghai Province,the land-surface model CLM3.0 was employed to simulate the freezing and melting of soil.The results indicate that the simulated soil temperature is higher than the observed soil temperature and the ultimate thawing date is earlier than the observed date during the melting period.During the freezing period,the simulated soil temperature is lower than the observed soil temperature and the ultimate freezing of the deep soil is earlier than that observed.Overall,the simulation of freezing is better than that of melting,and the simulation of a shallow layer is better than that of a deeper layer.In the original CLM3.0,it is assumed that frozen soil begins to melt when the soil temperature exceeds 0C,which is inconsistent with observations.The critical freeze-thaw temperature was calculated according to thermodynamics equations and the freeze-thaw condition was modified.In this work,the melting rate for frozen soil was reduced using the modified scheme,and the simulated soil temperature was lowered. Meanwhile,the refreezing of soil during the melting season was well simulated and more closely matched observations.Additionally,it was found that the rates of melting and freezing differ,with the former being slower than the latter,but refreezing during the melting season is rather quick. | XIA Kun 1,2,3,LUO Yong 2,4,5 & LI WeiPing 2 1 Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China 2National Climate Center,China Meteorological Administration,Beijing 100081,China 3Graduate University of Chinese Academy of Sciences,Beijing 100049,China 4 Center for Earth System Science,Tsinghua University,Beijing 100084,China 5Key Laboratory of Earth System Numerical Simulation,Ministry of Education,Beijing 100084,China | 2011 | Chinese Science Bulletin2011，56，20： | 14 |
| 10 | An approach to determining the local boundaries of voltage stability region with wind farms in power injection space显示文摘A new approach to determining the local boundaries of voltage stability region in power injection space (IVSR) for power system with wind farms is presented. It can be used for power system voltage stability analysis and on-line security assessment with considering the output uncertainty of the wind farms. Firstly, power flow tracing and double dispatching are used to determine the generators that are closely related to the wind farms, in order to balance the power fluctuations caused by the wind speed variation. Then, modal analysis is used to get the key generators to achieve an effective dimension reduction for IVSR. Finally, the forecasting output power (or wind speed) of wind farms is divided into several intervals. For each interval, the corresponding local IVSR boundaries can be calculated by the method based on small disturbance. Moreover, parallel process is used to accelerate the computing speed. The presented approach is validated by several power systems. It can be revealed that the approach can give the local IVSR boundaries at different wind speeds and has a good engineering application prospect. | MU YunFei & JIA HongJie Key Laboratory of Power System Simulation and Control of Ministry of Education, Tianjin University, Tianjin 300072, China | 2010 | Science China(Technological Sciences)2010，53，12： | 13 |
| 11 | Pollution characteristics of atmospheric fine particles and their secondary components in the atmosphere of Shenzhen in summer and in winter显示文摘Two field measurements for atmospheric fine particles were conducted in Baoan district of Shenzhen during the summer and winter in 2004. Totally 30 sets of 24 h samples were collected, and then the mass concentrations and chemical compositions were determined. The seasonal varia- tions and secondary pollution characteristics of fine particles during the sampling periods were dis-cussed with meteorological factors. The results show that seasonal variations of atmospheric particles are significant in Shenzhen. The average mass concentrations of PM2.5 and PM10 in summer were 35 μg·m-3 and 57 μg·m-3, respectively, and those in winter were 99 μg·m-3 and 135 μg·m-3, respec-tively. The concentrations of both PM2.5 and PM10 in winter increased 184% and 137%, respectively, compared to those in summer. PM2.5 accounted for 61% and 75% of PM10 in summer and in winter, respectively, indicating severe fine particle pollution in Shenzhen. During the summer and winter sampling periods, the mean OC/EC ratios were 3.4 and 1.6, respectively. The estimated secondary organic carbon (SOC) averagely accounted for 56% and 6% of the total OC in summer and in winter, respectively, which implies a major contribution of SOC to OC in summer. During the continuous high temperature period in summer, both the concentrations and fractions of secondary aerosol compo-nents in PM2.5 were highly elevated, suggesting severe secondary pollution again. The prevailing wind was from South China Sea in summer, and the air quality was good. The prevailing wind in winter was from China's Mainland to the north, and the polluted air mass led to poor air quality. | NIU Yuwen1,2,HE Lingyan1,2,HU Min2,ZHANG Jing2 & ZHAO Yunliang2 1. Shenzhen Graduate School of Peking University,Shenzhen 518055,China 2. State Joint Key Laboratory of Environmental Simulation and Pollution Control,College of Environmental Sciences,Peking University,Beijing 100871,China | 2006 | Science China Chemistry2006，49，5： | 12 |
| 12 | High time resolution observation and statistical analysis of atmospheric light extinction properties and the chemical speciation of fine particulates显示文摘In recent years,the visibility deterioration caused by regional fine particulate pollution becomes one of the crucial air pollution problems in the urban areas of our country.The rapid variation of visibility and fine particulates make it difficult to estimate the relationship between them precisely and accurately unless high time resolution observation data can be accessed.This study aims to fill this gap in the field of atmospheric science by establishing a formula using multiple linear regressions.Excellent fitting goodness (R2=0.913,n=3167) was obtained using 10 min average of high-resolution real-time light scattering coefficients,light absorption coefficients,main chemical speciation concentration in PM1 and some meteorological parameters from 17 Jan to 16 Feb,2009.It shows that the average light extinction coefficient during the observation in the winter of Shenzhen was measured to be 290 ± 183 Mm?1,consisting of 72% of light scattering and 21% of absorption.In terms of the percentage contribution of PM1 chemical species to the total light extinction,the organic matter was estimated to be most with an average of 45%,followed by ammonium sulfate with an average of 24%.The contributions of black carbon and ammonium nitrate were 17% and 12%,respectively.Besides,the diurnal variation of light extinction was investigated as well in this study. | YAO TingTing1,HUANG XiaoFeng1,HE LingYan1,HU Min2,SUN TianLe1,XUE Lian1,LIN Yun1,ZENG LiWu1 & ZHANG YuanHang2 1Key Laboratory for Urban Habitat Environmental Science and Technology,School of Environment and Energy,Peking University Shenzhen Graduate School,Shenzhen 518055,China 2State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and Engineering,Peking University,Beijing 100871,China | 2010 | Science China Chemistry2010，53，8： | 10 |
| 13 | Landuse/landcover changes in Zhangye oasis of Hexi Corridor显示文摘Taking two f alse color composite Landsat 5 TM (Thematic Mapper) images of band 4,3,2 taken in 1995 and 2000 as data resources, this paper carried out study on LUCC of Zhan gye oasis in recent five years by interpretation according to land reso urces classification system of 1:100,000 Resources and Environmental Data base of the Chinese Academy of Sciences. The results show that great changes have taken place in landuse/landcover in Zhangye oasis since 1 995: (1) Changes of landuse structure show that cropland and land for urban c onstruction and built-up area increased, on the contrary, water area an d grassland decreased. These changes reflect the deterioration of eco-e nvironment and the acceleration of urbanization, and also indicate the problems existing in the arrangement of water and land resources betw een the upper and lower reaches of the Heihe River. (2) Regional diff erences of landuse/landcover are evident, characterized by following asp ects: in Sunan County located in Qilian Mountain area, unused land an d grassland decreased, but cropland and land for urban construction an d built-up area increased. In Minle and Shandan counties located in f oothills, unused land, water area and cropland decreased, but grassland and land for urban construction and built-up area increased. In Zhan gye City, Linze County and Gaotai County located in plain area of th e middle reaches of the Heihe River, unused land, water area and gra ssland decreased, while woodland, cropland and land for urban construction and built-up area increased. | MENG Jijun,WU Xiuqin,LI Zhengguo(Department of Urban and Environmental Scien ce, Peking University, Laboratory of Analysis and Simulation of Earth Surface P rocesses, the Ministry of Education, Beijing 100871, China) | 2003 | Journal of Geographical Sciences2003，13，1： | 9 |
| 14 | Distributions of dimethylsulfide in the Bohai Sea and Yellow Sea of China显示文摘Dimethylsulfide(DMS) measurements in the surface seawater of China eastern coastline were conducted during March 9—10, 1993 in Bohai Sea along the cruise from Dalian to Tianjin and during September 24—25, 1994 in Yellow Sea along the cruise from Shanghai to Qingdao. On the cruise in Bohai Sea DMS concentrations varied from 0.11 to 2.63 nmol/L with an average of 1.31 nmol/L, while DMS flux was estimated to be 0.85 μmol/(m 2·d) with the range of 0.04—3.12 μmol/(m 2·d). On the cruise in Yellow Sea DMS concentrations varied from 0.95 to 7.48 nmol/L with an average of 2.89 nmol/L, and DMS flux was estimated to be 7.94 μmol/(m 2·d) with the range of 0.11—18.88 μmol/(m 2·d). Variations in DMS concentrations along the latitude in Yellow Sea were observed larger than those along the longitude in Bohai Sea. DMS concentrations and fluxes had a similar spatial trend both in Bohai Sea and Yellow Sea with the correlation coefficients of 0.75 and 0.64, respectively. | HU Min *, TANG Xiao-yan, LI Jin-long, MA Qi-ju (State Joint Key Laboratory of Environmental Simulation and Pollution Control Center for Environmental Sciences, Peking University, Beijing 100871, China. | 2003 | Journal of Environmental Sciences2003，15，6： | 8 |
| 15 | Eco-environmental water requirement for wetlands in Huang-Huai-Hai Area, China显示文摘Based on the related literature and the analysis of the relationship between wetland ecosystem and hydroperiod, the estimating and classifying methods of eco-environmental water requirement for wetlands are established. The data collected from Huang-Huai-Hai Area are from the electronic map (1∶250000) of China National Topographical Database of 1997 and the historical statistics since the 1980s.The results indicate that the minimum eco-environmental water requirement for wetlands is 16.98×109 m3 and the optimal one is 38.38×109 m3 in the studied area. For the five wetland nature reserves covered in the area, the values are 1.47×109 m3 and 3.31×109 m3 respectively. The comparisons of the mentioned minimum water requirement with the status water use, which is 17.05×109 m3 for wetland ecosystem (1997 as the status year), suggest that the water use has not met the minimum eco-environmental water requirement in the Haihe and Huanghe Basins of the studied area. However, the status water use guarantees and exceeds the minimum eco-environmental water requirement in the Shandong Peninsula and the Huaihe Basin. Based on the eco-environmental programming and water resource planning of the studied area, the study establishes the water requirement of the year of 2010, 2030, 2050, when the eco-environmental water requirement for wetlands is 18.30×109 m3, 21.64×109 m3 and 26.76×109 m3, respectively. | GUI Baoshan and YANG Zhifeng(1. Institute of Environmental Sciences, Beijing Normal University State Key Joint Laboratory of Environmental Simulation and Pollution Control, Beijing 100875, China 2. Institute of Water Sciences, Beijing Normal University Key Laboratory for Water and Sediment Sciences, Ministry of Education, Beijing 100875, China) | 2002 | Progress in Natural Science:Materials International2002，12，11： | 8 |
| 16 | Shape optimization of 3D curved slots and its application to the squirrel-cage elastic support design显示文摘The squirrel-cage elastic support is one of the most important components of an aero-engine rotor system.A proper structural design will favor the static and dynamic performances of the system.In view of the deficiency of the current shape optimization techniques,a new mapping approach is proposed to define shape design variables based on the parametric equations of 3D curves and surfaces.It is then applied for the slot shape optimization of a squirrel-cage elastic support.To this end,an automatic design procedure that integrates the Genetic Algorithm (GA) is developed to solve the problem.Two typical examples with different shape constraints are considered.Numerical results provide reasonable optimum designs for the improvement of stiffness and strength of the squirrel-cage elastic support. | WANG Dan,ZHANG WeiHong*,WANG ZhenPei & ZHU JiHong Engineering Simulation and Aerospace Computing,The Key Laboratory of Contemporary Design & Integrated Manufacturing Technology,Northwestern Polytechnical University,Xi’an 710072,China | 2010 | Science China(Physics,Mechanics & Astronomy)2010，53，10： | 8 |
| 17 | Heterogeneous reaction of SO_2 on TiO_2 particles显示文摘The heterogeneous reaction of SO2 on TiO2 particles was studied using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS).The influences of the oxygen concentration,relative humidity (RH),and ultraviolet (UV) light illumination (λ=365 nm) intensity on the reaction were investigated.The main product of the heterogeneous reaction of SO2 on TiO2 particles was sulfate with UV illumination and sulfite without it.The production of sulfate was promoted significantly with UV illumination or water,and there was a synergistic effect when both were present.In the dry system without UV,the heterogeneous reaction of SO2 on TiO2 particles was found to be second-order for SO2 and the initial uptake coefficient,BET,was determined to be 1.94 × 10-6.With UV and RH=40%,the reaction order was first-order and the initial uptake coefficient was 1.35 × 10-5. | SHANG Jing,LI Jia & ZHU Tong State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and Engineering,Peking University,Beijing 100871,China | 2010 | Science China Chemistry2010，53，12： | 8 |
| 18 | Estimation methods of eco-environmental water requirements: Case study显示文摘Supplying water to the ecological environment with certain quantity and quality is significant for the protection of diversity and the realization of sustainable development. The conception and connotation of eco-environmental water requirements, including the definition of the conception, the composition and characteristics of eco-environmental water requirements, are evaluated in this paper. The classification and estimation methods of eco-environmental water requirements are then proposed. On the basis of the study on the Huang-Huai-Hai Area, the present water use, the minimum and suitable water requirement are estimated and the cor-responding water shortage is also calculated. According to the interrelated programs, the eco-environmental water requirements in the coming years (2010, 2030, 2050) are estimated. The result indicates that the minimum and suitable eco-environmental water requirements fluc-tuate with the differences of function setting and the referential standard of water resources, and so as the water shortage. Moreover, the study indicates that the minimum eco-environmental water requirement of the study area ranges from 2.84×1010m3 to 1.02×1011m3, the suitable water requirement ranges from 6.45×1010m3 to 1.78×1011m3, the water shortage ranges from 9.1×109m3 to 2.16×1010m3 under the minimum water requirement, and it is from 3.07×1010m3 to 7.53×1010m3 under the suitable water requirement. According to the different values of the water shortage, the water priority can be allocated. The ranges of the eco-environmental water re-quirements in the three coming years (2010, 2030, 2050) are 4.49×1010m3?1.73×1011m3, 5.99×10m3?2.09×1011m3, and 7.44×1010m3?2.52×1011m3, respectively. | YANG Zhifeng1,2, CUI Baoshan1 & LIU Jingling 1. School of Environment, Beijing Normal University, Beijing 100875, China 2. State Key Joint Laboratory of Environmental Simulation and Pollution Control, Beijing 100875, China | 2005 | Science China Earth Sciences2005，48，8： | 7 |
| 19 | Microstructure and shear strength of the brazed joint of Ti(C,N)-based cermet to steel显示文摘Firm joins were obtained between Ti(C,N)-based cermet and steel with Ag-Cu-Zn-Ni filler metal by vacuum brazing. The effects of technological parameters such as brazing temperature, holding time, and filler thickness on the shear strength of the joints were investigated. The microstructure of welded area and the reaction products of the filler metal were examined by scanning electron microscopy (SEM), metallographic microscope (OM), energy-dispersive X-ray analysis (EDS), and X-ray diffraction (XRD). The brazing temperature of 870°C, holding time of 15 min, and filler thickness of 0.4 mm are a set of optimum technological parameters, under which the maximum shear strength of the joints, 176.5 MPa, is achieved. The results of microstructure show that the wettability of the filler metal on Ti(C,N)-based cermet and steel is well. A mutual solution layer and a diffusion layer exist between the welding base materials and the filler metal. | YE Dameng, XIONG Weihao, Zhang Xiuhai, QU Jun, and YAO Zhenghua State Key Laboratory of Plastic Forming Simulation and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, China | 2010 | Rare Metals2010，29，1： | 7 |
| 20 | Application and Comparison of SST Model in Numerical Simulation of the Axial Compressors显示文摘The shear-stress transport(SST)turbulence model is incorporated into Navier-Stokes equations to simulate a turbomachinery flowfield.A staggered finite volume method is used to make the mean flow equations and turbulence model equations strongly coupled and enhance the stability of the numerical computation.The implicit treatment of the source terms is applied to the SST model.A steady state solution is obtained using five-stage Runge-Kutta time-stepping scheme with local time stepping and residual smoothing to accelerate convergence. The wall distance d,a key parameter in the SST model,is solved by a partial differential equation.The validations of the code are conducted on rotor 37,wp11 at design and off-design conditions by comparison with measurements and the Spalart-Allmaras(SA)turbulence model.The flow within the tip is calculated with a multi-block grid. | YIN Song~1,JIN Donghai~2,GUI Xingmin~3 and ZHU Fang Aero-Engines Simulation Research Center,School of Jet Propulsion,Beijing University of Aeronautics and Astronautics, Beijing,100191,China | 2010 | Journal of Thermal Science2010，19，4： | 7 |
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